1. Technical Field
The present invention relates to an electronic device and more particularly, to a case of an electronic device having a ground circuit function.
2. Description of Related Art
Along with the progress in semiconductor technology, various electronic devices are developed with functions of portability and convenience such as notebooks or portable electronic devices or the like. However, a human body carries more or less static electricity, such that the electrostatic charges are transmitted from fingers to the inside of a notebook and causes the electrostatic discharge (ESD) when the user operates the notebook. The electrostatic current formed by the electrostatic discharge is transmitted from the opening of the case (e.g., the opening of a connector) to the circuit board disposed within the notebook and damages the elements of the circuit board. Similarly, if an electric leakage occurs in the elements of the notebook, the electric current of the electric leakage may be transmitted from the opening to the outside of the case and it may cause the user to get an electric shock when the user touches the touch panel.
To solve the above problems, fabricating the case with metal is one of the resolving ways, but it may increase the weight of the notebook and does not comply with the compactness trend. In addition, a metal layer being sputtered to the internal wall of the case is another resolving way of the above problems. After the circuit board with a connector being assembled to the case, a conductive cloth or a conductive sponge is disposed and electrically bridged the connector and the metal layer of the case. Though the resolving way described above needs less and simple element, the conductive cloth or conductive sponge has to be attached manually. Thus, it has problems of positioning or tolerance, and further if a re-processing is needed, the stickiness of the detached conductive cloth or the conductive sponge may be reduced, or the metal layer of the case may be peeled off with the conductive cloth or the conductive sponge.
On the other hand, another resolving way is to dispose a metal spring between the connector and the metal layer of the case to form a ground circuit. Though it may improve the aforementioned positioning or tolerance problem of the conductive cloth or the conductive sponge, the manufacturing cost of spring is much higher than the conductive cloth or the conductive sponge.